Hearing loss, from whatever cause, is seldom uniform over the wide range of frequencies recognized by the human ear. Suppression of the amplitude of the midrange sounds to those of the less favored ranges restores the relative value of different frequencies. Amplification restores the sound level over the entire range. Many well known electronic means are available for each of these functions.
Perception of orientation of received sounds is possible because the sounds arrive at the two ears at slightly different times. Phase comparison by the brain is interpreted as the direction of the sound source.
Even smaller differences occur with sounds arriving at the upper and lower areas of the pinna of the human ear. These sounds are reflected into the auditory canal where they arrive at the cochlea completely intermixed. They are separated and separately processed by the brain. Phase comparisons produce specific knowledge of the angular elevation of the source of the sound.
Given the broad binaural hearing of youth, the brain is further able to sort sounds and concentrate its attention on specific sound qualities, enabling one to converse quietly even when assaulted by many other and louder noises.
As hearing is progressively impaired, the discriminatory abilities are lost. The goal of hearing supplementation is to restore all of these abilities. To do so, inputs equivalent to vertical separation are also required.
Multiple-element speaker systems, such as conventional stereo home entertainment equipment, provide a plurality of sound sources which are received at the ear simultaneously. The multiple sources provide an enhanced effect for the sound, usually music. However, the universal approach to multiple-element sound systems for both stereo (two-channel) and quad (four-channel) has been to place the speakers in the horizontal plane. The pick-up elements, microphones, are likewise placed in a corresponding horizontal plane such that the recording and reproduction of the sounds provide a horizontal dimension.
Conventional aids for hearing impaired persons do not provide the sound orientation of normal hearing. These aids produce confusing sounds which substantially diminish the useability of the devices.
Additional background information regarding multiple source sound systems is given in U.S. Pat. No. 4,322,744 to Austin N. Stanton.
There has been little or no development of sound systems which provide sound separation in planes other than the horizontal. The human ear can be responsive to sounds in the vertical dimension which have phase and amplitude variations just as it is responsive to such sounds in the horizontal dimension. Therefore, there exists a need for apparatus for providing dissimilar sounds to the human ear with the differing components being oriented in the vertical plane.